Growth and Characterization of Homoepitaxial GaN on N-face GaN Free-standing~Substrate by Plasma-Assisted Molecular-Beam Epitaxy

As compared to the commercial GaN based LED with the Ga-face GaN substrate, the GaN film grown along N-face GaN has been considered to have better current injection efficiency for GaN p-n junction. In this paper, we have studied the growth of GaN epi-layer on N-face GaN free-standing substrate. The N-face GaN free-standing substrate was prepared by hydride vapor phase epitaxy and its full width at half maximum is 469.2 arc-sec by X-ray analysis. The homoepitaxial GaN samples were grown atop the prepared N-face GaN free-standing substrate by plasma-assisted molecular-beam epitaxy under different growth conditions. The homoepitaxial GaN samples were characterized by the in-situ reflection high-energy electron diffraction, X-ray diffractometry, field emission secondary electron microscope, and atomic force microscope. In addition, the optical properties of the samples were analyzed by polarization-dependent photoluminescence.